Cranial Shape Variation Research Articles

Ecological and evolutionary factors in the morphological diversification of South American spiny rats

Understanding the processes underlying morphological diversification is a central goal in ecology and evolutionary biology and requires the integration of information about phylogenetic divergence and ecological niche diversity. In the present study, we use geometric morphometrics and comparative methods to investigate morphological diversification in Neotropical spiny rats of the family Echimyidae. Morphological diversification is studied as shape variation in the skull, comprising a structure composed of four distinct units: vault, base, orognathofacial complex, and mandible. We demonstrate association among patterns of variation in shape in different cranial units, levels of phylogenetic divergence, and ecological niche diversification. At the lower level of phylogenetic divergence, there is significant and positive concordance between patterns of phylogenetic divergence and cranial shape variation in all cranial units. This concordance may be attributable to the phylogenetic and shape distances being calculated between species that occupy the same niche. At higher phylogenetic levels of divergence and with ecological niche diversity, there is significant concordance between shape variation in all four cranial units and the ecological niches. In particular, the orognathofacial complex revealed the most significant association between shape variation and ecological niche diversity. This association may be explained by the great functional importance of the orognathofacial complex. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 98, 646–660.

Craniometric data supports demic diffusion model for the spread of agriculture into Europe.

BackgroundThe spread of agriculture into Europe and the ancestry of the first European farmers have been subjects of debate and controversy among geneticists, archaeologists, linguists and anthropologists. Debates have centred on the extent to which the transition was associated with the active migration of people as opposed to the diffusion of cultural practices. Recent studies have shown that patterns of human cranial shape variation can be employed as a reliable proxy for the neutral genetic relationships of human populations.Methodology/Principal FindingsHere, we employ measurements of Mesolithic (hunter-gatherers) and Neolithic (farmers) crania from Southwest Asia and Europe to test several alternative population dispersal and hunter-farmer gene-flow models. We base our alternative hypothetical models on a null evolutionary model of isolation-by-geographic and temporal distance. Partial Mantel tests were used to assess the congruence between craniometric distance and each of the geographic model matrices, while controlling for temporal distance. Our results demonstrate that the craniometric data fit a model of continuous dispersal of people (and their genes) from Southwest Asia to Europe significantly better than a null model of cultural diffusion.Conclusions/SignificanceTherefore, this study does not support the assertion that farming in Europe solely involved the adoption of technologies and ideas from Southwest Asia by indigenous Mesolithic hunter-gatherers. Moreover, the results highlight the utility of craniometric data for assessing patterns of past population dispersal and gene flow.

Variation in the digging apparatus of the subterranean silvery mole-rat, Heliophobius argenteocinereus (Rodentia, Bathyergidae): the role of ecology and geography

The skull of most subterranean tooth-digging rodents is markedly affected by their digging mode. In the present study, we investigated the cranial variation in a strictly subterranean, highly specialized Afrotropical tooth-digger, Heliophobius argenteocinereus (Bathyergidae, Rodentia), using a geometric morphometric approach and evaluated the effect of different factors on size and shape differences among four populations. No evidence for sexual dimorphism was found in skull size or shape. The cranial shape variation was large and influenced mainly by the type of habitat (miombo woodland versus farmland and grassland) and the latitudinal gradient. The dorsal side of the skull appears to be more plastic and adaptable to local environments, as well as more independent of size, than the ventral side. Only the shortening of the rostrum is presumably an adaptive process independent of size that leads to an increase of efficacy of the tooth-digging apparatus in Heliophobius, whereas the increase in the in-force and the more procumbent incisors both comprise size-related changes caused by ontogenetic allometric growth. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 97, 822–831.

It is all in the head: morphological basis for differences in bite force among colour morphs of the Dalmatian wall lizard

Males of the lizard Podarcis melisellensis occur in three distinct colours that differ in bite performance, with orange males biting harder than white or yellow ones. Differences in bite force among colour morphs are best explained by differences in head height, suggesting underlying variation in cranial shape and/or the size of the jaw adductors. To explore this issue further, we examined variation in cranial shape, using geometric morphometric techniques. Additionally, we quantified differences in jaw adductor muscle mass. No significant differences in size corrected head shape were found, although some shape trends could be detected between the colour morphs. Orange males have relatively larger jaw adductors than yellow males. Not only the mass of the external jaw adductors, but also that of the internal jaw adductors was greater for the orange morph. Data for other cranial muscles not related to biting suggest that this is not the consequence of an overall increase in robustness in orange individuals. These results suggest that differences in bite performance among morphs are caused specifically by an increase in the mass of the jaw adductor, which may be induced by differences in circulating hormone levels. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 96, 13–22.

Cranial shape variation and molecular phylogenetic structure of crested newts (Triturus cristatus superspecies: Caudata, Salamandridae) in the Balkans

In the present study, we investigated the degree of congruence between phylogeny, as inferred from mitochondrial (mt)DNA sequences, and cranium shape variation of crested newts (Triturus cristatus superspecies) in the Balkans. These newts belong to four phylogenetic clades defined by mtDNA analysis, and significantly differed in cranial shape. Allometry explained a high percentage of shape variation in crested newts. The clade-specific allometric slopes significantly diverged for both the ventral cranium and dorsal cranium, indicating that differences in shape between clades could not be a simple consequence of their difference in size. The analysis of hierarchical and spatial variation showed similarity in the patterns of global and spatially localized hierarchical variation of cranial shape. We also found significant congruence between the pattern of cranial shape variation and molecular phylogeny. The differences in morphology of Triturus dobrogicus in comparison to other crested newt clades, including marked differences in cranium shape, is discussed in the context of the evolution and ecology of crested newts. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 95, 348–360.

Geometric craniometric analysis of sexual dimorphism and ontogenetic variation: A case study based on two geographically disparate species, Aethomys ineptus from southern Africa and Arvicanthis niloticus from Sudan (Rodentia: Muridae)

Non-geographic morphometric variation, particularly at the level of sexual dimorphism and ontogenetic (age-related) variation, has been documented in rodents, and useful for establishing whether to analyse sexes separately or together, and for selecting adult specimens for subsequent data recording and analysis. However, such studies have largely been based on traditional morphometric analyses of linear measurements that mainly focus on overall size, rather than shape-related morphometric variation. Unit-free, landmark/outline-based geometric morphometric analyses are considered to offer a more appropriate tool for assessing shape-related morphometric variation. In this study, we used geometric cranial morphometric analysis to assess the nature and extent of sexual dimorphism and age variation within the Tete veld rat, Aethomys ineptus (Thomas and Wroughton, 1908) from southern Africa and the African Nile rat, Arvicanthis niloticus (Desmarest, 1822) from Sudan. The results obtained were in turn compared with previously published results based on independent geometric and traditional cranial morphometric data from the same sampled populations examined in the present study. While our geometric morphometric results detected statistically significant sexual dimorphism in cranial shape within Ar. niloticus only, previously published results based on traditional morphometric data failed to detect significant sexual dimorphism within this species. However, similar to previously published traditional morphometric data, our geometric morphometric results detected statistically significant age-related variation in cranial shape and size within both Ae. ineptus and Ar. niloticus, with individuals of age classes 5 and 6 being considered to represent adult specimens. Our results highlight the importance of carefully evaluating both size- and shape-related non-geographic morphometric variation prior to the analysis of geographic variation and the delineation of species. Erroneous conclusions of non-geographic variation may have implications in the interpretation of geographic and evolutionary processes that may be responsible for morphological differences at both the inter- and intra-specific levels.

Geographic Variation in Cranial Shape in the Pumpkin Toadlet (Brachycephalus Ephippium): A Geometric Analysis

Abstract The description of patterns of variation in any character system within well-defined species is fundamental for understanding lineage diversification and the identification of geographic units that represent opportunities for sustained evolutionary divergence. In this paper, we analyze intraspecific variation in cranial shape in the Pumpkin Toadlet, Brachycephalus ephippium–a miniaturized species composed of isolated populations on the slopes of the mountain ranges of southeastern Brazil. Shape variables were derived using geometric-statistical methods that describe shape change as localized deformations in a spatial framework defined by anatomical landmarks in the cranium of B. ephippium. By statistically weighting differences between landmarks that are not close together (changes at larger geometric scale), cranial variation among geographic samples of B. ephippium appears continuous with no obvious gaps. This pattern of variation is caused by a confounding effect between within-sample allometr...

The taxonomic implications of cranial shape variation in Homo erectus

The taxonomic status of Homo erectus sensu lato has been a source of debate since the early 1980s, when a series of publications suggested that the early African fossils may represent a separate species, H. ergaster. To gain further resolution regarding this debate, 3D geometric morphometric data were used to quantify overall shape variation in the cranial vault within H. erectus using a new metric, the sum of squared pairwise Procrustes distances (SSD). Bootstrapping methods were used to compare the H. erectus SSD to a broad range of human and nonhuman primate samples in order to ascertain whether variation in H. erectus most clearly resembles that seen in one or more species. The reference taxa included relevant phylogenetic, ecological, and temporal analogs including humans, apes, and both extant and extinct papionin monkeys. The mean cranial shapes of different temporogeographic subsets of H. erectus fossils were then tested for significance using exact randomization tests and compared to the distances between regional groups of modern humans and subspecies/species of the ape and papionin monkey taxa. To gauge the influence of sexual dimorphism on levels of variation, comparisons were also made between the mean cranial shapes of single-sex samples for the reference taxa. Results indicate that variation in H. erectus is most comparable to single species of papionin monkeys and the genus Pan, which included two species. However, H. erectus encompasses a limited range of variation given its extensive geographic and temporal range, leading to the conclusion that only one species should be recognized. In addition, there are significant differences between the African/Georgian and Asian H. erectus samples, but not between H. ergaster (Georgia + Africa, excluding OH 9 and Daka) and H. erectus sensu stricto. This finding is in line with expectations for intraspecific variation in a long-lived species with a wide, but probably discontinuous, geographic distribution.

Cranial shape and size variation in human evolution: structural and functional perspectives

A GLIMPSE INTO MODERN PALEOANTHROPOLOGY: In the last decades, paleoanthropology has been deeply modified, changing from a descriptive and historical science to a more quantitative and analytical discipline. The covariation of multiple traits is investigated to study the evolutionary changes of the underlying anatomical models, mostly through the introduction of digital biomedical imaging procedures and of computed geometrical analyses supported by multivariate statistics. FUNCTIONAL CRANIOLOGY: The evolution of the human cranium is consequently considered in terms of functional and structural relationships between its components, largely influenced by the allometric variations associated with the increase in the relative cranial capacity. In the human genus, the changes in the face, base, and neurocranium are characterised by a mosaic variation, in which adaptations, secondary consequences, and stochastic factors concur to generate a set of anatomical possibilities and constraints. SYSTEMIC PERSPECTIVES TO THE EVOLUTION OF THE HUMAN CRANIAL MORPHOLOGY: Concepts like morphological modularity, anatomical integration, and heterochrony represent key issues in the development of the current human evolutionary studies.

On the Cranial Osteology of Chiroptera. I. Pteropus (Megachiroptera: Pteropodidae)

Although detailed anatomical descriptions of skull morphology are available for representatives of many mammalian orders, no such descriptive work exists for bats, a group that comprises over 20% of extant mammalian species. In this paper, we provide a detailed description of the skull of Pteropus (Mammalia: Chiroptera: Megachiroptera: Pteropodidae) and establish a system of cranial nomenclature following the Nomina Anatomica Veterinaria. Based on a series of specimens of Pteropus lylei, we describe the skull as a whole and the morphology of external surfaces of 24 bones (7 rostral, 16 cranial, plus the mandible) and 17 teeth. We describe internal surfaces and additional bones of disarticulated skulls of Pteropus livingstonii and use material from the same species to describe the middle ear ossicles and the petrosal bone. We include a description of the hyoid apparatus and larynx based on Pteropus tonganus and a description of the deciduous dentition based on Pteropus hypomelanus. Using a sectioned fetus, we determine the content and homology of all cranial foramina present in the skull of Pteropus. We outline the ontogenetic changes from newborn pups to adults, considering changes in skull shape and the sequence of bone fusion and tooth eruption. Based on selected comparisons to other megabats, we discuss broad patterns of variation in general cranial shape, and interspecific variation in sutures, foramina, processes, and dentition. Overall, this work establishes a descriptive and nomenclatorial benchmark for chiropteran skull anatomy in line with similar works in other mammalian orders, with the aim of creating common ground for comparative, phylogenetic, and functional studies of the bat skull, including comparisons with other mammals.

Congruence of hierarchical, localized variation in cranial shape and molecular phylogenetic structure in spiny rats, genus Trinomys (Rodentia: Echimyidae)

Congruence between patterns of localized, hierarchical variation in cranial shape and topological, molecular phylogenetic structure was investigated in a monophyletic lineage of Neotropical spiny rats of the genus Trinomys. Levels of organizational complexity in shape were assessed from two-dimensional coordinates of anatomical landmarks for dorsal, ventral and lateral views of the cranium, and the scale of variation in cranial shape was decomposed hierarchically using the statistical formalism of geometric morphometrics. The patterns of variation in cranial shape were evaluated for the five taxa of Trinomys in terms of ordinations in the reduced space of relative warps, with the scores of partial warps weighted to emphasize the hierarchical localization of shape differences in different geometric scales. The fit of the morphological shape data to the molecular phylogeny and analysis of the correlation between measures of the differences in shape and molecular phylogenetic distances demonstrated that only variation in small, localized scales in cranial shape in the lateral view of the cranium was congruent with molecular phylogenetic structure. The significance and perspectives of the application of geometric descriptors of shape and the identification of scales of variation for the study of morphological and molecular evolution are discussed. © 2003 The Linnean Society of London, Biological Journal of the Linnean Society, 2003, 80, 385–396.

Cranial allometry, phylogeography, and systematics of large-bodied papionins (primates: Cercopithecinae) inferred from geometric morphometric analysis of landmark data.

The cranial morphology of the African Old World monkeys Mandrillus, Papio, and Theropithecus (i.e., baboons) has been the subject of a number of studies investigating their systematic relationships, patterns of scaling, and growth. In this study, we use landmark-based geometric morphometrics and multivariate analysis to assess the effects of size, sex, taxonomy, and geographic location on cranial shape. Forty-five landmarks were digitized in three dimensions on 452 baboon crania and subjected to generalized Procrustes analysis (GPA), which standardizes geometric size but leaves scaling-based shape differences in the data. The resulting shape coordinates were submitted to regression analysis, principal components analysis (PCA), partial least-squares (PLS) analysis, and various clustering techniques. Scaling (shape differences correlated with size) was the largest single factor explaining cranial shape variation. For instance, most (but not all) of the shape differences between the sexes were explained by size dimorphism. However, central tendencies of shape clearly varied by taxon (both specific and subspecific) even after variations in size and sex were adjusted out. Within Papio, about 60% of the size- and sex-adjusted shape variations were explained by the geographic coordinates of the specimen's provenance, revealing a stepped cline in cranial morphology, with the greatest separation between northern and southern populations. Based on evidence from genetic studies, and the presence of at least two major hybrid/interbreeding zones, we interpret the phylogeographic pattern of cranial variation as indicating that these populations are best ranked as subspecies of a single species, rather than as two or more distinct biological species. This objective approach can be applied to other vertebrate species or species groups to help determine the taxonomic rank of problematic taxa.

Patterns of cranial shape variation in the Papionini (Primates: Cercopithecinae).

Traditional classifications of the Old World monkey tribe Papionini (Primates: Cercopithecinae) recognized the mangabey genera Cercocebus and Lophocebus as sister taxa. However, molecular studies have consistently found the mangabeys to be diphyletic, with Cercocebus and Mandrillus forming a clade to the exclusion of all other papionins. Recent studies have identified cranial and postcranial features which distinguish the Cercocebus-Mandrillus clade, however the detailed similarities in cranial shape between the mangabey genera are more difficult to reconcile with the molecular evidence. Given the large size differential between members of the papionin molecular clades, it has frequently been suggested that allometric effects account for homoplasy in papionin cranial form. A combination of geometric morphometric, bivariate, and multivariate methods was used to evaluate the hypothesis that allometric scaling contributes to craniofacial similarities between like-sized papionin taxa. Patterns of allometric and size-independent cranial shape variation were subsequently described and related to known papionin phylogenetic relationships and patterns of development. Results confirm that allometric scaling of craniofacial shape characterized by positive facial allometry and negative neurocranial allometry is present across adult papionins. Pairwise comparisons of regression lines among genera revealed considerable homogeneity of scaling within the Papionini, however statistically significant differences in regression lines also were noted. In particular, Cercocebus and Lophocebus exhibit a shared slope and significant vertical displacement of their allometric lines relative to other papionins. These findings give no support to narrowly construed hypotheses of uniquely shared patterns of allometric scaling, either between sister taxa or across all papionins. However, more general allometric trends do appear to account for a substantial proportion of papionin cranial shape variation, most notably in those features which have influenced traditional morphological phylogenies. Examination of size-uncorrelated shape variation gives no clear support to molecular phylogenies, but underscores the absence of morphometric similarities between the mangabey genera when size effects are controlled. Patterns of allometric and size-uncorrelated shape variation indicate conservatism of cranial form in non- Theropithecus papionins, and suggest that Papio represents the primitive morphometric pattern for the African papionins. Lophocebus exhibits a divergent morphometric pattern, clearly distinguishable from other papionins, most notably Cercocebus. These results clarify patterns of cranial shape variation among the extant Papionini and lay the groundwork for studies of related fossil taxa.

GEOGRAPHIC VARIATION IN CRANIAL MORPHOLOGY IN THRICHOMYS APEREOIDES (RODENTIA: ECHIMYIDAE). I. GEOMETRIC DESCRIPTORS AND PATTERNS OF VARIATION IN SHAPE

Geometric descriptors were used to describe variation in cranial shape within and among populations of the echimyid rodent Thrichomys apereoides from localities in northeastern, central, and southeastern Brazil. Variation in shape based on dorsal, ventral, and lateral views of the skull, as inferred from contribution of uniform components and partial warps, was attributable to localized rather than global changes in morphology of the skull. Each view of the skull showed characteristic variability in shape among populations and provided different perspectives on patterns of geographic variation. The lateral view of the skull provided the most information content in terms of populations that share similarity in cranial shape and continuity over geographic space.

GEOGRAPHIC VARIATION IN CRANIAL MORPHOLOGY IN THRICHOMYS APEREOIDES (RODENTIA: ECHIMYIDAE). II. GEOGRAPHIC UNITS, MORPHOLOGICAL DISCONTINUITIES, AND SAMPLING GAPS

Abstract Geographic variation in cranial shape was examined in 20 samples of the echimyid rodent Thrichomys apereoides from northeastern, central, and southeastern Brazil. Canonical variate analysis and a dendrogram based on geometric shape descriptors revealed 2 groups of populations diagnosable by features of cranial shape and geographic continuity. The observed morphological discontinuity between the 2 groups of populations corresponds with a gap in sampling of T. apereoides, as represented by the museum series used. A positive, significant relationship between morphological and geographic distances was found among populations within each of the 2 groups but not between populations in the 2 groups. The indirect, statistical approach suggests that discontinuity in cranial shape in T. apereoides results from historical processes of differentiation rather than from an artifact caused by a gap in the available samples.

SKULL SHAPE AND SIZE DIVERGENCE IN DOLPHINS OF THE GENUS SOTALIA: A TRIDIMENSIONAL MORPHOMETRIC ANALYSIS

A study of cranial shape in dolphins of genus Sotalia was done using 104 specimens (92 from localities along the Brazilian coast and 12 from the Amazon River basin). Twenty-two cranial landmarks, assumed to be homologous, were selected for analysis. The first 2 principal components of aligned coordinates explained 40.6% of the total variation in cranial shape. Although no sexual dimorphism was detected (P = 0.811), shape differences among populations of Sotalia were highly significant (P < 0.000001). The 1st and 2nd principal components of shape showed that the Sotalia population from the Amazon basin differed in cranial shape from marine populations. Based on differences in geometric shape, a discriminant analysis of 3 linear measurements between landmarks provided an equation that classified skulls as belonging to Amazonian or marine populations. Based on these results and evidence from several other divergent character systems and life history attributes, we suggest the use of Sotalia guianensis for marine dolphins and S. fluviatilis for Amazonian dolphins.

First Known Tibia of an Early Javanese Hominid.

Previous articleNext article No AccessReportsFirst Known Tibia of an Early Javanese Hominid1Shuji Matsu’ura, Megumi Kondo, Fachroel Aziz, Sudijono, Shuichiro Narasaki, and Naotune WatanabeShuji Matsu’uraDepartment of Human Biological Studies, Faculty of Human Life and Environmental Science, Ochanomizu University, Tokyo 112‐8610, Japan (Matsu’ura and Kondo)/Geological Research and Development Centre, Bandung 40122, Indonesia (Aziz and Sudijono)/Department of Anthropology, Gunma Museum of Natural History, Gunma 370‐2345, Japan (Narasaki) / University of Tokyo, Tokyo 113‐0033, Japan (Watanabe). 15 iv 99 Search for more articles by this author , Megumi KondoDepartment of Human Biological Studies, Faculty of Human Life and Environmental Science, Ochanomizu University, Tokyo 112‐8610, Japan (Matsu’ura and Kondo)/Geological Research and Development Centre, Bandung 40122, Indonesia (Aziz and Sudijono)/Department of Anthropology, Gunma Museum of Natural History, Gunma 370‐2345, Japan (Narasaki) / University of Tokyo, Tokyo 113‐0033, Japan (Watanabe). 15 iv 99 Search for more articles by this author , Fachroel AzizDepartment of Human Biological Studies, Faculty of Human Life and Environmental Science, Ochanomizu University, Tokyo 112‐8610, Japan (Matsu’ura and Kondo)/Geological Research and Development Centre, Bandung 40122, Indonesia (Aziz and Sudijono)/Department of Anthropology, Gunma Museum of Natural History, Gunma 370‐2345, Japan (Narasaki) / University of Tokyo, Tokyo 113‐0033, Japan (Watanabe). 15 iv 99 Search for more articles by this author , SudijonoDepartment of Human Biological Studies, Faculty of Human Life and Environmental Science, Ochanomizu University, Tokyo 112‐8610, Japan (Matsu’ura and Kondo)/Geological Research and Development Centre, Bandung 40122, Indonesia (Aziz and Sudijono)/Department of Anthropology, Gunma Museum of Natural History, Gunma 370‐2345, Japan (Narasaki) / University of Tokyo, Tokyo 113‐0033, Japan (Watanabe). 15 iv 99 Search for more articles by this author , Shuichiro NarasakiDepartment of Human Biological Studies, Faculty of Human Life and Environmental Science, Ochanomizu University, Tokyo 112‐8610, Japan (Matsu’ura and Kondo)/Geological Research and Development Centre, Bandung 40122, Indonesia (Aziz and Sudijono)/Department of Anthropology, Gunma Museum of Natural History, Gunma 370‐2345, Japan (Narasaki) / University of Tokyo, Tokyo 113‐0033, Japan (Watanabe). 15 iv 99 Search for more articles by this author , and Naotune WatanabeDepartment of Human Biological Studies, Faculty of Human Life and Environmental Science, Ochanomizu University, Tokyo 112‐8610, Japan (Matsu’ura and Kondo)/Geological Research and Development Centre, Bandung 40122, Indonesia (Aziz and Sudijono)/Department of Anthropology, Gunma Museum of Natural History, Gunma 370‐2345, Japan (Narasaki) / University of Tokyo, Tokyo 113‐0033, Japan (Watanabe). 15 iv 99 Search for more articles by this author Department of Human Biological Studies, Faculty of Human Life and Environmental Science, Ochanomizu University, Tokyo 112‐8610, Japan (Matsu’ura and Kondo)/Geological Research and Development Centre, Bandung 40122, Indonesia (Aziz and Sudijono)/Department of Anthropology, Gunma Museum of Natural History, Gunma 370‐2345, Japan (Narasaki) / University of Tokyo, Tokyo 113‐0033, Japan (Watanabe). 15 iv 99PDFPDF PLUSFull Text Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by Current Anthropology Volume 41, Number 2April 2000 Sponsored by the Wenner-Gren Foundation for Anthropological Research Article DOIhttps://doi.org/10.1086/300136 Views: 50Total views on this site Citations: 10Citations are reported from Crossref PDF download Crossref reports the following articles citing this article:Qian Wang, Phillip V. Tobias An old species and a new frontier: Some thoughts on the taxonomy of Homo erectus, Anthropological Review 64 (Jun 2001): 9–20.https://doi.org/10.18778/1898-6773.64.01Shuji Matsu’ura Toward the resolution of controversial chronologies for the World Heritage Site of Sangiran : Dating the first appearance of Homo erectus in the island of Java, The Quaternary Research (Daiyonki-Kenkyu) 61, no.11 (Mar 2022): 1–25.https://doi.org/10.4116/jaqua.61.2108KAREN L. BAAB, YAHDI ZAIM Global and local perspectives on cranial shape variation in Indonesian Homo erectus, Anthropological Science 125, no.22 (Jan 2017): 67–83.https://doi.org/10.1537/ase.170413Erick Setiyabudi, Akio Takahashi, Yosuke Kaifu First Certain Fossil Record of Orlitia borneensis (Testudines: Geoemydidae) from the Pleistocene of Central Java, Indonesia, Current Herpetology 35, no.22 (Aug 2016): 75–82.https://doi.org/10.5358/hsj.35.75Liora Kolska Horwitz, Patricia Smith, Marina Faerman, Elisabetta Boaretto, Irina Segal The application of biometry and LA-ICP-MS to provenance isolated bones: a study of hominin remains from Oumm Qatafa Cave, Judean Desert, Archaeological and Anthropological Sciences 3, no.33 (Mar 2011): 245–262.https://doi.org/10.1007/s12520-011-0056-1Yousuke Kaifu, Yahdi Zaim, Hisao Baba, Iwan Kurniawan, Daisuke Kubo, Yan Rizal, Johan Arif, Fachroel Aziz New reconstruction and morphological description of a Homo erectus cranium: Skull IX (Tjg-1993.05) from Sangiran, Central Java, Journal of Human Evolution 61, no.33 (Sep 2011): 270–294.https://doi.org/10.1016/j.jhevol.2011.04.002Karen L. Baab Cranial Shape in Asian Homo erectus: Geographic, Anagenetic, and Size-Related Variation, (Jul 2010): 57–79.https://doi.org/10.1007/978-90-481-9094-2_6Sheela Athreya Patterning of geographic variation in Middle Pleistocene Homo frontal bone morphology, Journal of Human Evolution 50, no.66 (Jun 2006): 627–643.https://doi.org/10.1016/j.jhevol.2005.11.005Samuel Márquez, Kenneth Mowbray, G J Sawyer, Teuku Jacob, Adam Silvers New fossil hominid calvaria from Indonesia-Sambungmacan 3, The Anatomical Record 262, no.44 (Feb 2001): 344–368.https://doi.org/10.1002/ar.1046Eric Delson, Katerina Harvati, David Reddy, Leslie F. Marcus, Kenneth Mowbray, G. J. Sawyer, Teuku Jacob, Samuel Márquez The Sambungmacan 3 Homo erectus calvaria: A comparative morphometric and morphological analysis, The Anatomical Record 262, no.44 (Feb 2001): 380–397.https://doi.org/10.1002/ar.1048

Sexual Dimorphism as It Relates to Natural History of Leopard Lizards (Crotaphytidae: Gambelia)

Sexual dimorphism is a phenomenon that occurs in a variety of animal taxa, and its occurrence can reflect and/or influence crucial aspects of the natural history of organisms. We examined the external morphology of three lizard species, Gambelia sila, G. wislizenii, and G. copei. Gambelia sila shows the prevalent sexually dimorphic condition among iguanian lizards of males attaining a larger head relative to body size (snout-vent length) and larger overall body size than females, whereas in G. wislizenii and G. copei, females attain a larger body size than males. We performed a detailed morphometric examination of these three taxa to (1) characterize interspecific differences in sexual dimorphism among these three closely related lizards, (2) test the hypothesis that sexual dimorphism in cranial shape exists in G. wislizenii and G. copei, and (3) examine intersexual body size and cranial shape variation among G. wislizenii populations inhabiting major North American geophysical regions. Morphometric analyses support the results of previous studies. Cranial shape dimorphism is present in some G. wislizenii populations, particularly those of the Great Basin, and in G. copei. Interregional comparisons reveal that G. wislizenii populations vary both in the degree of intersexual body and head size differences as well as in cranial shape dimorphism. Among regional groups, body and head size and cranial shape dimorphism exhibit an inverse relationship. These patterns of morphological variation are correlated with aspects of the ecology, behavior, and phylogenetic history of these taxa.